| Constraining the time variation of the coupling constants from cosmic microwave background: effect of \Lambda_{QCD} (2009) | |||||||||
Abstract | |||||||||
| We investigate constraints on the time variation of the fine structure constant between the recombination epoch and the present epoch, $\Delta\alpha/\alpha \equiv (\alpha_{rec} - \alpha_{now})/\alpha_{now}$, from cosmic microwave background (CMB) taking into account simultaneous variation of other physical constants, namely the electron mass $m_{e}$ and the proton mass $m_{p}$. In other words, we consider the variation of Yukawa coupling and the QCD scale $\Lambda_{QCD}$ in addition to the electromagnetic coupling. We clarify which parameters can be determined from CMB temperature anisotropy in terms of singular value decomposition. Assuming a relation among variations of coupling constants governed by a single scalar field (the dilaton), the 95 % confidence level (C.L.) constraint on $\Delta\alpha/\alpha$ is found to be $-8.28 \times 10^{-3} < \Delta\alpha/\alpha < 1.81 \times 10^{-3}$, which is tighter than the one obtained by considering only the change of $\alpha$ and $m_{e}$. We also obtain the constraint on the time variation of the proton-to-electron mass ratio $\mu \equiv m_{p}/m_{e}$ to be $-0.52 < \Delta\mu/\mu < 0.17$ (95 % C.L.) under the same assumption.. Comment: 23 pages, 4 figures; references added | |||||||||
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